Add concise project overview to README

[Copilot]

The issue asks for a clearer understanding of the project. This update adds a short, scannable overview of the architecture so readers can quickly grasp how the Electron app and AI backend fit together.

• Documentation: project overview
  • Added a focused “项目概览/Project Overview” section in both README.md and README.en.md
  • Summarizes main-process responsibilities, preload/renderer boundaries, and the FastAPI/LangGraph backend interface and port

Example excerpt:

## Project Overview

- The Electron main process handles window/tray management, the SQLite store, image storage, and backups. The default data directory is `Documents/OriginNotes` (configurable in-app).
- The preload layer exposes IPC via `window.electronAPI`, and the renderer uses Vue 3 + Pinia + TipTap for the note UI.
- The AI backend is FastAPI + LangGraph on `127.0.0.1:8765`, handling chat, vector sync, and RAG search. The renderer calls it over HTTP.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• registry.npmmirror.com
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node node /home/REDACTED/work/_temp/ghcca-node/node/bin/npm install --legacy-peer-deps (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

了解我的项目

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.